TW201518453A - Adhesive composition, adhesive film and surface protection film - Google Patents

Abstract

The present invention provides an adhesive composition that has excellent antistatic performance, that has excellent adhesive strength balance in the peel rate of a slow rate region and a high rate region, and that further also has excellent durability performance and reworking performance, and that can prevent the occurrence of defects such as depressions by external stress. In accordance with the present invention, an adhesive composition which contains 100 parts by weight of a (meth)acrylic-based polymer that has an ionic value of 0.01 to 8.0 and that is formed by copolymerizing, as blended amounts with respect to 100 parts by weight of the (meth)acrylic-based polymer, 55 to 97.5 parts by weight of alkyl (meth)acrylates having a C4 to C10 alkyl group, 1 to 30 parts by weight of alkyl (meth)acrylates having a C14 to C18 alkyl group, 0.1 to 15 parts by weight of hydroxyl group-containing copolymerizable monomers, 0.1 to 2 parts by weight of carboxyl group-containing copolymerizable monomers, and 0.1 to 5 parts by weight of a cross-linking agent, wherein an antistatic agent is an ionic compound having a melting point of 30 to 50 DEG C, is provided.

Description

Adhesive composition, adhesive film and surface protection film

The present invention relates to an adhesive composition having antistatic properties and an adhesive film using the adhesive composition to form an adhesive layer having antistatic properties on at least one side of a resin film, and a surface protective film . Further, the present invention relates to a surface protective film used in a manufacturing step of a liquid crystal display. More specifically, the present invention relates to an optical member for protecting a polarizing plate, a phase difference plate, an antireflection film, and the like by adhering to a surface of an optical member such as a polarizing plate, a phase difference plate, or an antireflection film constituting a liquid crystal display. The surface protective film for the surface is composed of an adhesive composition, and a surface protective film using the adhesive composition.

In the manufacturing step of an optical member such as a polarizing plate, a phase difference plate, or an antireflection film which is a member constituting a liquid crystal display, a surface protective film for temporarily protecting the surface of the optical member is adhered. Such a surface protective film is used only in the step of manufacturing an optical member, and when the optical member is assembled to a liquid crystal display, it is removed from the optical member and removed. Since such a surface protective film for protecting the surface of the optical member is used only in the manufacturing step, it is also generally referred to as a "step film".

In the surface protective film used in the step of manufacturing an optical member, an adhesive layer is formed on one surface of an optically transparent polyethylene terephthalate (PET) resin film, but A release film that has been subjected to release treatment is attached to the adhesive layer to protect the adhesive layer until it is attached to the optical member. In addition, an optical member such as a polarizing plate, a phase difference plate, or an anti-reflection film is subjected to optical evaluation such as display performance, color tone, contrast, and impurity incorporation of the liquid crystal display panel in a state in which the surface protective film is bonded. Inspection, therefore, as a performance requirement for the surface protective film, it is required that the adhesive layer does not contain bubbles or impurities. In addition, when the surface protective film is peeled off from an optical member such as a polarizing plate, a retardation film, or an antireflection film, the static electricity generated by the static electricity generated when the adhesive layer is peeled off from the adherend may be peeled off. It affects the failure of the electrical control circuit of the liquid crystal display, and therefore, the adhesive layer is required to have excellent antistatic properties. Further, when a surface protective film is bonded to an optical member such as a polarizing plate, a retardation film, or an antireflection film, for some reasons, the surface protective film may be temporarily peeled off and then the surface protective film may be reattached again. Peeling (reworkability) on the optical member as the adherend. Further, at this time, it is required not to contaminate the adherend, that is, the phenomenon that the so-called adhesive residue does not occur. Further, when the surface protective film is finally peeled off from an optical member such as a polarizing plate, a retardation film, or an antireflection film, it is required to be peeled off quickly. That is, it is required that the change in the peeling force due to the peeling speed is small, so that the peeling can be quickly peeled off even in the case of high-speed peeling.

As described above, in recent years, from the viewpoint of easy handling when using a surface protective film, the adhesive layer constituting the surface protective film is required to have the following properties: (1) at a peeling speed in a low speed region and a high speed region, adhesion is obtained. Balance; (2) prevent the occurrence of adhesive residue; (3) have excellent antistatic properties; and (4) have rework performance. However, even if the performance requirements for the adhesive layer constituting the surface protective film can be satisfied, that is, even if the individual performance requirements in the above (1) to (4) can be respectively satisfied, the adhesion of the surface protective film is satisfied at the same time. The agent layer has all the performance requirements of (1) to (4), which is a very difficult problem. In the present specification, the "low speed region" means a region in which the peeling speed is in the vicinity of 0.3 m/min; and the "high speed region" refers to a region in which the peeling speed is in the vicinity of 30 m/min.

For example, regarding (1) obtaining a balance of adhesive force at a peeling speed of a low speed region and a high speed region, and (2) preventing occurrence of adhesive residue, the following suggestions are known.

a copolymer of a (meth)acrylic acid alkyl ester having an alkyl group having 7 or less carbon atoms and a carboxyl group-containing copolymerizable compound as a main component, and which is crosslinked by a crosslinking agent. In the acrylic adhesive layer, when the adhesive is adhered for a long period of time, the adhesive moves to the side of the adherend to adhere to the adherend, and the adhesion to the adherend is increased with time. The problem. In order to avoid this problem, there is known a technical solution in which an adhesive layer is used which uses an alkyl (meth)acrylate having an alkyl group having 8 to 10 carbon atoms and has A copolymer of a copolymer of a hydroxyl group-containing copolymer and a crosslinking agent obtained by crosslinking it with a crosslinking agent (Patent Document 1). In addition, a technical solution is provided in which an adhesive layer is provided by mixing a small amount of an alkyl (meth) acrylate and a carboxyl group in the same copolymer as described above. A copolymer of a copolymerizable compound and a binder layer obtained by crosslinking it with a crosslinking agent. However, when it is used for surface protection of a plastic sheet or the like having a low surface tension and a smooth surface, problems arise in that separation due to separation during processing or storage, and in the field of manual operation. When the peeling is performed at a high speed, the removability is poor.

In order to solve these problems, an adhesive composition is proposed which is characterized in that a) an alkyl (meth)acrylate having an alkyl group having 8 to 10 carbon atoms as a main component To 100 parts by weight of the alkyl (meth)acrylate, b) 1 to 15 parts by weight of a carboxyl group-containing copolymerizable compound, and c) 3 to 100 parts by weight of an aliphatic carboxylic acid having 1 to 5 carbon atoms; A binder composition in which a copolymer of a monomer mixture is obtained by a vinyl ester, and a crosslinking agent having a carboxyl group equivalent or more of the above b) component is blended in the copolymer (Patent Document 2). In the adhesive composition described in Patent Document 2, peeling phenomenon such as separation does not occur during processing or storage, and the adhesive strength is not greatly increased over time, and the removability is excellent. In addition, even if it is stored for a long period of time, especially in a high-temperature environment, it can be re-peeled with a small force. At this time, no adhesive remains on the adherend, and even in the case of high-speed peeling, Small forces are then peeled off.

In addition, as a method for imparting antistatic properties to the surface protective film, (3) excellent antistatic performance, a method of mixing an antistatic agent into a base film, or the like has been proposed. As the antistatic agent, for example, various cationic antistatic agents of (a) a 4-grade ammonium salt, a pyridinium salt, a cationic group having a primary to tertiary amine group, and the like; (b) a sulfonate group and a sulfate salt are disclosed. Anionic antistatic agent such as an anion group such as a phosphate group, a phosphonate group or a phosphonate group; (c) an amphoteric antistatic agent such as an amino acid or an amine sulfate; (d) an amino alcohol or a glycerin And a nonionic antistatic agent such as a polyethylene glycol; (e) a polymer type antistatic agent obtained by polymerizing the antistatic agent as described above (Patent Document 3). Further, in recent years, it has been proposed to include such an antistatic agent in a base film or directly on the surface of the base film and directly include the adhesive layer.

Further, regarding (4) reworkability, for example, an adhesive composition is proposed which is blended with 0.0001 to 10 parts by weight of an isocyanate compound per 100 parts by weight of the acrylic resin. A curing agent and a specific phthalate oligomer are obtained (Patent Document 4). Patent Document 4 describes, as a main monomer, an alkyl acrylate having an alkyl group having a carbon number of from 2 to 12, an alkyl methacrylate having an alkyl group having a carbon number of from 4 to 12, or the like. The component may contain a monomer component containing other functional groups such as a carboxyl group-containing monomer. In general, it is preferred to contain 50% by weight or more of the above-mentioned main monomer, and it is desirable that the content of the monomer component containing a functional group is 0.001 to 50% by weight, preferably 0.001 to 25% by weight, more preferably 0.01 to 25% by weight. . The adhesive composition described in Patent Document 4 has a small change in the cohesive force and the adhesive force over time even under high temperature or high temperature and high humidity, and exhibits an excellent effect on the adhesion of the curved surface. Reworkability. In general, when the adhesive layer is soft, the adhesive remains easily and the reworkability is easily lowered. That is, it is difficult to peel off after the wrong bonding, and it is difficult to re-stick. From this point of view, in order to impart reworkability, it is necessary to crosslink a monomer having a functional group such as a carboxyl group to the main component so that the adhesive layer has a certain hardness. [Prior Art Literature] [Patent Literature]

[Patent Document 1] Japanese Patent Laying-Open No. Hei 11-256111 (Patent Document 3): JP-A-H11-070629 (Patent Document 4): Japan Special Report No. 8-199130

(The problem to be solved by the invention)

In the prior art, the adhesive layer constituting the surface protective film is required to have the following properties: (1) obtaining a balance of adhesive force at a peeling speed in a low speed region and a high speed region; and (2) preventing occurrence of adhesive residue. (3) has excellent antistatic properties; and (4) has rework performance. However, even if the performance requirements of the individual items (1) to (4) above can be satisfied, the entire performance requirements of the adhesive layer of the surface protective film cannot be satisfied. Further, in recent years, after the adhesive is applied onto the resin film to form the adhesive layer, there is a problem that the adhesive layer has defects such as dents due to external stress. Therefore, as a performance requirement for the adhesive layer, in addition to the above four items, (5) prevention of defects such as dents due to external stress are required.

The present invention has been made in view of the above circumstances, and an object thereof is to provide an excellent antistatic property, excellent balance of adhesion at a peeling speed in a low speed region and a high speed region, and excellent durability and reworkability. An adhesive composition, an adhesive film, and a surface protective film capable of preventing defects such as dents caused by external stress. (method of solving the problem)

In order to solve the above problems, the present invention provides an adhesive composition which is an adhesive composition containing an antistatic agent and a (meth)acrylic polymer, wherein the above (methyl) is relative to 100 parts by weight The (meth)acrylic polymer is 55 to 97.5 parts by weight of an alkyl (meth)acrylate having an alkyl group having 4 to 10 carbon atoms, 1 in terms of a compounding amount of the acrylic polymer. ～30 parts by weight of an alkyl (meth)acrylate having an alkyl group having 14 to 18 carbon atoms, 0.1 to 15 parts by weight of a hydroxyl group-containing copolymerizable monomer, and 0.1 to 2 parts by weight of a carboxyl group-containing monomer The copolymerizable monomer is copolymerized; the binder composition further contains 0.1 to 5 parts by weight of a crosslinking agent with respect to 100 parts by weight of the (meth)acrylic polymer; The acrylic polymer has an acid value of 0.01 to 8.0; and the antistatic agent is an ionic compound having a melting point of 30 to 50 °C.

Further, the alkyl (meth)acrylate having an alkyl group having 4 to 10 carbon atoms is preferably selected from the group consisting of butyl (meth)acrylate, isobutyl (meth)acrylate, and (methyl). Ethyl acrylate, hexyl (meth) acrylate, heptyl (meth) acrylate, octyl (meth) acrylate, isooctyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, One or more of a compound group consisting of decyl (meth)acrylate, isodecyl (meth)acrylate, decyl (meth)acrylate, and isodecyl (meth)acrylate; the foregoing has a carbon atom The alkyl (meth)acrylate having a number of 14 to 18 alkyl groups is preferably selected from the group consisting of isotetradecyl (meth)acrylate and isohexadecyl (meth)acrylate. One of a group of compounds consisting of isostearyl acrylate, tetradecyl (meth) acrylate, cetyl (meth) acrylate, and octadecyl (meth) acrylate Or two or more.

Further, it is preferred to contain a polyether modified siloxane compound having an HLB value of 7 to 15 as an antistatic adjuvant.

Further, the hydroxyl group-containing copolymerizable monomer is preferably selected from the group consisting of 8-hydroxyoctyl (meth)acrylate, 6-hydroxyhexyl (meth)acrylate, and (meth)acrylic acid 4. -hydroxybutyl ester, 2-hydroxyethyl (meth)acrylate, N-hydroxy(meth)acrylamide, N-hydroxymethyl(meth)acrylamide, N-hydroxyethyl(meth)propene At least one or more of the compound groups consisting of guanamine.

Further, the carboxyl group-containing copolymerizable monomer is selected from the group consisting of (meth)acrylic acid, carboxyethyl (meth)acrylate, carboxypentyl (meth)acrylate, and 2-(methyl)acrylonitrile. Ethyl hexahydrophthalic acid, 2-(methyl) propylene methoxypropyl hexahydrophthalic acid, 2-(methyl) propylene methoxyethyl phthalate, 2-(A Acryloxyethyl succinic acid, 2-(methyl) propylene oxiranyl ethyl maleic acid, carboxy polycaprolactone mono (meth) acrylate, 2-(methyl) propylene decyloxy One or more of the compound groups consisting of ethyltetrahydrophthalic acid.

Further, it is preferred to contain a polyether-modified siloxane compound having an HLB value of 7 to 15 and a molecular weight of 10,000 or less as an antistatic adjuvant.

Further, the crosslinking agent is preferably a trifunctional or higher isocyanate compound.

Further, the present invention provides an adhesive film characterized in that an adhesive layer is formed on one surface of a resin film, and the adhesive layer is formed by crosslinking the adhesive composition.

Further, the present invention provides a surface protective film which uses the aforementioned adhesive film.

Further, the present invention provides a surface protective film for a polarizing plate which uses the above-mentioned adhesive film.

Further, the present invention provides a surface protective film for optics which uses the above-mentioned adhesive film.

Further, the present invention provides an adhesive film for bonding a polarizing plate and a display panel, which uses the above-mentioned adhesive film.

Further, the present invention provides an adhesive film for bonding an optical film material constituting a polarizing plate, which uses the above-mentioned adhesive film.

Further, the present invention provides an optical film for a touch panel which uses the above-mentioned adhesive film.

Further, the present invention provides an optical film for electronic paper using the above-mentioned adhesive film. (Effect of the invention)

According to the present invention, it is possible to satisfy all the properties required for the adhesive layer of the surface protective film which cannot be solved in the prior art, and it is possible to obtain excellent antistatic properties and prevent the occurrence of the adhesive residue.

Hereinafter, the present invention will be described based on an ideal embodiment. The adhesive composition of the present invention is an adhesive composition containing an antistatic agent and a (meth)acrylic polymer, and preferably, it is: with respect to 100 parts by weight of the aforementioned (meth)acrylic polymer The (meth)acrylic polymer is composed of 55 to 97.5 parts by weight of an alkyl (meth)acrylate having an alkyl group having 4 to 10 carbon atoms, and 1 to 30 parts by weight. The alkyl (meth)acrylate having an alkyl group having 14 to 18 carbon atoms, 0.1 to 15 parts by weight of a hydroxyl group-containing copolymerizable monomer, and 0.1 to 2 parts by weight of a carboxyl group-containing copolymerizable monomer; Copolymerized; the adhesive composition further contains 0.1 to 5 parts by weight of a crosslinking agent with respect to 100 parts by weight of the (meth)acrylic polymer, and the (meth)acrylic polymer The acid value is 0.01 to 8.0, and the antistatic agent is an ionic compound having a melting point of 30 to 50 °C.

The alkyl (meth)acrylate having an alkyl group having 4 to 10 carbon atoms is preferably selected from the group consisting of butyl (meth)acrylate, isobutyl (meth)acrylate, and (methyl). Amyl acrylate, hexyl (meth) acrylate, heptyl (meth) acrylate, octyl (meth) acrylate, isooctyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, ( One or more of a compound group consisting of methacrylic acid decyl acrylate, isodecyl (meth) acrylate, decyl (meth) acrylate, and isodecyl (meth) acrylate. It is preferable to contain 55 to 97.5 parts by weight of an alkyl (meth)acrylate having an alkyl group having 4 to 10 carbon atoms with respect to 100 parts by weight of the (meth)acrylic polymer.

The alkyl (meth)acrylate having an alkyl group having 14 to 18 carbon atoms is preferably selected from the group consisting of isotetradecyl (meth)acrylate and isohexadecyl (meth)acrylate. Base ester, isostearyl (meth)acrylate, myristyl (meth)acrylate, cetyl (meth)acrylate, stearic acid (meth)acrylate, (meth)acrylic acid Alkyl ester, pentadecyl (meth)acrylate, cetyl (meth)acrylate, heptadecyl (meth)acrylate, octadecyl (meth)acrylate One or more of the compound groups. The alkyl group having 14 to 18 carbon atoms is a (meth)acrylic acid alkyl ester of a branched alkyl group or a linear alkyl group (meth)acrylic acid alkyl ester. It is preferred to contain 1 to 30 parts by weight of an alkyl (meth)acrylate having an alkyl group having 14 to 18 carbon atoms with respect to 100 parts by weight of the (meth)acrylic polymer.

When only the (meth)acrylic acid alkyl ester monomer (having 4 to 10 carbon atoms) having a relatively large number of carbon atoms is used in consideration of the wettability (wettability) of the adhesive to the adherend, It will simply soften the adhesive. When the alkyl (meth) acrylate contains a linear alkyl group or a branched alkyl group, when the number of carbon atoms is about 6 to 8, the homopolymer has the lowest glass transition point (Tg). When the number of carbon atoms is larger than the above, the Tg tends to be high, but the flexibility is maintained. Therefore, by copolymerizing an alkyl (meth)acrylate having an alkyl group having 14 to 18 carbon atoms, it is possible to eliminate defects such as dents while maintaining wettability to the adherend.

Examples of the hydroxyl group-containing copolymerizable monomer include hydroxyalkyl (meth)acrylates and hydroxyl group-containing (meth)acrylamides. Preferably, the hydroxyl group-containing copolymerizable monomer is selected from the group consisting of 8-hydroxyoctyl (meth)acrylate, 6-hydroxyhexyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, (A) a group of compounds consisting of 2-hydroxyethyl acrylate, N-hydroxy(meth) acrylamide, N-methylol (meth) acrylamide, and N-hydroxyethyl (meth) acrylamide At least one of the above. The content of the hydroxyl group-containing copolymerizable monomer is preferably 0.1 to 15 parts by weight based on 100 parts by weight of the above (meth)acrylic polymer.

The carboxyl group-containing copolymerizable monomer is preferably selected from the group consisting of (meth)acrylic acid, carboxyethyl (meth)acrylate, carboxypentyl (meth)acrylate, and 2-(methyl)acrylonitrile. Ethyl hexahydrophthalic acid, 2-(methyl) propylene methoxypropyl hexahydrophthalic acid, 2-(methyl) propylene methoxyethyl phthalate, 2-(A Acryloxyethyl succinic acid, 2-(methyl) propylene oxiranyl ethyl maleic acid, carboxy polycaprolactone mono (meth) acrylate, 2-(methyl) propylene decyloxy One or more of the compound groups consisting of ethyltetrahydrophthalic acid. The content of the carboxyl group-containing copolymerizable monomer is preferably 0.1 to 2 parts by weight based on 100 parts by weight of the above (meth)acrylic polymer.

For the adhesive composition of the present invention, it is preferred to crosslink the adhesive polymer when the adhesive layer is formed. As a method of performing the crosslinking reaction, crosslinking may be carried out by photocrosslinking such as ultraviolet rays (UV), but it is preferred that the binder composition contains a crosslinking agent. Examples of the crosslinking agent include a difunctional or trifunctional or higher isocyanate compound, a difunctional or trifunctional or higher epoxy compound, a difunctional or trifunctional or higher acrylate compound, a metal chelate compound, and the like. Among them, a polyisocyanate compound (difunctional or trifunctional or higher isocyanate compound) is preferable, and a trifunctional or higher isocyanate compound is more preferable. The content of the crosslinking agent is preferably 0.1 to 5 parts by weight based on 100 parts by weight of the above (meth)acrylic polymer.

The trifunctional or higher isocyanate compound may be a polyisocyanate compound having at least three or more isocyanate (NCO) groups in one molecule. The polyisocyanate compound includes a classification of an aliphatic isocyanate, an aromatic isocyanate, an acyclic isocyanate, an alicyclic isocyanate, and the like, and the present invention may be any of them. Specific examples of the polyisocyanate compound include aliphatic isocyanate compounds such as hexamethylene diisocyanate (HDI), isophorone diisocyanate (IPDI), and trimethylhexamethylene diisocyanate (TMDI). Diphenylmethane diisocyanate (MDI), benzodimethyl diisocyanate (XDI), hydrogenated dimethyl diisocyanate (H6XDI), dimethyl diphenylene diisocyanate (TOID), toluene diisocyanate (TDI An aromatic isocyanate compound. Examples of the trifunctional or higher isocyanate compound include a biuret modified product or a isocyanurate modified product of a diisocyanate (a compound having two NCO groups in one molecule), and a trimethylol group. An adduct (polyol modified product) of a trivalent or higher polyvalent alcohol (a compound having at least three or more OH groups in one molecule) such as propane (TMP) or glycerin.

In order to impart antistatic properties, the adhesive composition of the present invention preferably contains an antistatic agent. The antistatic agent is preferably a solid at normal temperature (for example, 30 ° C). More specifically, the antistatic agent is preferably an ionic compound having a melting point of 30 to 50 °C. The antistatic agent may be a 4-stage ammonium salt type ionic compound containing an acrylonitrile group. Since these antistatic agents have a low melting point and a long-chain alkyl group, they are presumed to have high affinity with a (meth)acrylic polymer.

The antistatic agent having an ionic compound having a melting point of 30 to 50 ° C is an ionic compound having a cation and an anion, and examples of the cation include a pyridinium cation, an imidazolium cation, a pyrimidine cation, a pyrazolium cation, and a pyrrole. a nitrogen-containing phosphonium cation such as a phosphonium cation or an ammonium cation, or a phosphonium cation or a sulfonium cation, and the anion is a hexafluorophosphate (PF ₆ ^- ), a thiocyanate (SCN ^- ), an alkylbenzenesulfonate ( A compound of an inorganic or organic anion such as RC ₆ H ₄ SO ₃ ^- ), perchlorate (ClO ₄ ^- ) or tetrafluoroborate (BF ₄ ^- ). A compound having a melting point of 30 to 50 ° C can be obtained by selecting the chain length of the alkyl group, the position and number of the substituents, and the like. The preferred cation is a 4-stage nitrogen sulfonium cation, and examples thereof include a 4-alkylpyridinium cation such as 1-alkylpyridinium (having a substituent or a substituent at a carbon atom of 2 to 6), and 1,3. a 4-stage imidazolium cation such as a dialkylimidazolium (a carbon atom at the 2, 4 or 5 position may have a substituent or a substituent), or a 4-stage ammonium cation such as a tetraalkylammonium. The content of the antistatic agent as the ionic compound having a melting point of 30 to 50 ° C is preferably 0.1 to 5.0 parts by weight based on 100 parts by weight of the (meth)acrylic polymer.

The quaternary ammonium salt type ionic compound containing an acrylonitrile group is an ionic compound having a cation and an anion, and the cation is (meth) propylene decyloxyalkyltrialkylammonium (R ₃ N) ⁺ -C _n H _2n -OCOCQ=CH ₂ , wherein Q=H or CH ₃ , R=alkyl), etc., contains 4-methylammonium (meth)acryloyl group, and anion is hexafluorophosphate (PF) ₆ ^- ), thiocyanate (SCN ^- ), organic sulfonate (RSO ₃ ^- ), perchlorate (ClO ₄ ^- ), tetrafluoroborate (BF ₄ ^- ), F-containing quinone (R) A compound of an inorganic or organic anion such as ^F ₂ N ^- ). (PEI) containing a root of F (R ^F ₂ N ^-) of R & lt ^F, include trifluoromethanesulfonic acyl, sulfo pentafluoroethyl acyl group such as a perfluoroalkyl sulfonic acyl, sulfo-fluoro-acyl. As the F-containing quinone imine root, bis(fluorosulfonyl) quinone imide [(FSO ₂ ) ₂ N ^- ], bis(trifluoromethanesulfonyl) fluorenylene [[CF _3] SO ₂ ) ₂ N ^- ], bis(sulfonyl sulfonyl) ruthenium [(C ₂ F ₅ SO ₂ ) ₂ N ^- ] and the like. The quaternary ammonium salt type ionic compound containing an acrylonitrile group is preferably copolymerized in the above (meth)acrylic polymer in an amount of 0.1 to 5.0% by weight.

Specific examples of the antistatic agent are not particularly limited, but specific examples of the ionic compound having a melting point of 30 to 50 ° C include 1-octylpyridinium dodecylbenzenesulfonate and 1-ten Dialkylpyridinium thiocyanate, 3-methyl-1-dodecylpyridinium hexafluorophosphate, 1-dodecylpyridinium dodecylbenzenesulfonate, 4-methyl- 1-octylpyridinium hexafluorophosphate or the like. Further, specific examples of the quaternary ammonium salt type ionic compound containing an acrylonitrile group include dimethylaminomethyl (meth) acrylate hexafluorophosphate methyl salt [(CH ₃ ) ₃ N ⁺ CH ₂ OCOCQ=CH ₂ •PF ₆ ^- , wherein Q=H or CH ₃ ], dimethylaminoethyl (meth) acrylate bis(trifluoromethanesulfonyl) quinone imine methyl salt [(CH ₃ ) ₃ N ⁺ (CH ₂ ) ₂ OCOCQ=CH ₂ •(CF ₃ SO ₂ ) ₂ N ^- , where Q=H or CH ₃ ], dimethylaminomethyl(meth)acrylic acid Ester bis(fluorosulfonyl) quinone imine methyl salt [(CH ₃ ) ₃ N ⁺ CH ₂ OCOCQ=CH ₂ • (FSO ₂ ) ₂ N ^- , wherein Q = H or CH ₃ ] and the like.

The adhesive composition of the present invention preferably contains a polyether modified siloxane compound having an HLB value of from 7 to 15. The polyether-modified siloxane compound is a siloxane compound having a polyether group, and further comprises a siloxane unit having a polyether group in addition to a usual siloxane unit (-SiR ¹ ₂ -O-) -SiR ¹ (R ² O(R ³ O) _n R ⁴ )-O-). Here, R ¹ represents one or two or more alkyl groups or aryl groups, R ² and R ³ represent one or two or more alkylene groups, and R ⁴ represents one or two or more alkyl groups, fluorenyl groups and the like ( End base). The polyether group may, for example, be a polyoxyalkylene group ((C ₂ H ₄ O) _n ) or a polyoxypropylene group ((C ₃ H ₆ O) _n ). The molecular weight of the polyether-modified siloxane compound is preferably 10,000 or less in terms of weight average molecular weight (Mw). From the viewpoint of compatibility with the acrylic adhesive, the compatibility of the HLB is low and the molecular weight is low, but if the polyether modified siloxane compound having a low molecular weight is high, even if the HLB is relatively high (for the adhesive) The compatibility is slightly lower, and excellent antistatic properties can also be obtained. Further, the content of the polyether-modified siloxane compound is preferably 0.01 to 0.5 parts by weight based on 100 parts by weight of the (meth)acrylic polymer. HLB is a hydrophilic-lipophilic balance (a ratio of hydrophilicity to lipophilicity) prescribed in, for example, JIS K3211 (surfactant terminology). The polyether-modified oxoxane compound can be obtained, for example, by grafting an organic compound having an unsaturated bond and a polyoxyalkylene group to a polyorganosiloxane having a decyl group by a hydrogenation oximation reaction. Obtained from the main chain of the alkane. Specifically, a dimethyl methoxy oxane-methyl (polyoxyethylene) decane copolymer, dimethyl methoxy oxane-methyl (polyoxyethylene) decane-methyl (poly) A propylene oxide) siloxane copolymer, a dimethyl methoxy oxane-methyl (polyoxypropylene) siloxane copolymer, or the like. By blending the above polyether-modified siloxane compound with the binder composition, the adhesion and reworkability of the adhesive can be improved. Further, the polyether-modified oxirane compound functions as an antistatic adjuvant by being used in combination with an antistatic agent which is an ionic compound having a melting point of 30 to 50 °C.

The adhesive composition of the present invention may contain a crosslinking inhibitor. Examples of the crosslinking inhibitor include methyl acetonitrile acetate, ethyl acetate, octyl acetate, oleyl acetate, lauryl acetate, stearyl acetate, and the like. Β -ketoester, β -diketone such as acetamidineacetone, 2,4-hexanedione, benzamidineacetone or the like. These are ketoenol tautomer compounds, and in the binder composition using a polyisocyanate compound as a crosslinking agent, by blocking the isocyanate group of the crosslinking agent, it is possible to suppress adhesion after bonding with the crosslinking agent. The excessive increase in viscosity or gelation of the composition of the agent can prolong the shelf life of the adhesive composition. The crosslinking inhibitor is preferably a ketoenol tautomer compound, and particularly preferably at least one selected from the group consisting of ethyl acetate and ethyl acetate. In the case where the crosslinking inhibitor is added, the content of the crosslinking inhibitor relative to 100 parts by weight of the (meth)acrylic polymer is preferably 1.0 to 5.0 parts by weight.

The adhesive composition of the present invention may contain a crosslinking catalyst. When a polyisocyanate compound is used as a crosslinking agent, the crosslinking catalyst may be a substance that functions as a catalyst for the reaction (crosslinking reaction) of the (meth)acrylic polymer and the crosslinking agent. Examples thereof include an amine compound such as a tertiary amine, an organotin compound such as an organotin compound, an organic lead compound, or an organic zinc compound. Examples of the tertiary amine include a trialkylamine, N,N,N',N'-tetraalkyldiamine, N,N-dialkylamino alcohol, and triethylenediamine. A porphyrin derivative, a piperidine derivative or the like. Examples of the organotin compound include a dialkyl tin oxide, a fatty acid salt of a dialkyl tin, a fatty acid salt of stannous, and the like. The crosslinking catalyst is preferably an organotin compound, and particularly preferably at least one selected from the group consisting of dioctyltin oxide and dioctyltin dilaurate. When the crosslinking catalyst is added, the content of the crosslinking catalyst is preferably 0.01 to 0.5 parts by weight based on 100 parts by weight of the (meth)acrylic polymer.

The adhesive composition of the present invention may contain a polyether compound. The polyether compound is a compound having a polyalkylene oxide, and examples thereof include polyether polyols such as polyalkylene glycol and derivatives thereof. The alkylene group which is contained in the polyalkylene glycol and the polyalkyleneoxy group may, for example, be an ethyl group, a propyl group or a butyl group, but is not limited thereto. The polyalkylene glycol may be a copolymer of two or more kinds of polyalkylene glycols such as polyethylene glycol, polypropylene glycol, and polytetramethylene glycol. Examples of the copolymer of the polyalkylene glycol include polyethylene glycol-polypropylene glycol, polyethylene glycol-polybutylene glycol, polypropylene glycol-polybutylene glycol, and polyethylene glycol-polypropylene glycol-polybutylene. The diol or the like may be a block copolymer or a random copolymer. Examples of the derivative of the polyalkylene glycol include a polyoxyalkylene monoalkyl ether, a polyoxyalkylene dialkyl ether, and the like, and a polyoxyalkylene alkyl ether. Polyoxyalkylene alkyl alkenyl ethers such as alkenyl ethers, polyoxyalkylene dialkyl ethers, polyoxyalkylene monoaryl ethers, polyoxyalkylene diaryl ethers, etc. Polyoxyalkylene fatty acid esters such as polyethers, polyoxyalkylene alkyl phenyl ethers, polyoxyalkylene glycol monoesters, polyoxyalkylene glycol di fatty acid esters, polyoxidation Alkyl sorbitan fatty acid ester, polyoxyalkylene alkylamine, polyoxyalkylene diamine, and the like. Here, examples of the alkyl ether in the polyalkylene glycol derivative include a lower alkyl ether such as methyl ether or diethyl ether, and a higher alkyl ether such as lauryl ether or octadecyl ether. Examples of the alkenyl ether in the polyalkylene glycol derivative include a vinyl ether, an allyl ether, and an oleyl ether. Further, examples of the fatty acid ester in the polyalkylene glycol derivative include saturated fatty acid esters such as acetate and stearate, and unsaturated fatty acid esters such as (meth) acrylate and oleate. . The polyether compound is preferably a compound containing an ethylene oxide, more preferably a compound containing a polyoxyethylene group.

When the polyether compound has a polymerizable functional group, it can also be copolymerized with a (meth)acrylic polymer. The polymerizable functional group is preferably an ethylenic functional group such as a (meth)acryl group, a vinyl group or an allyl group. Examples of the polyether compound having a polymerizable functional group include a polyalkylene glycol mono(meth)acrylate, a polyalkylene glycol di(meth)acrylate, and an alkoxy polyalkylene group. Alcohol (meth) acrylate, polyalkylene glycol monoallyl ether, polyalkylene glycol diallyl ether, alkoxy polyalkylene glycol allyl ether, polyalkylene A diol monovinyl ether, a polyalkylene glycol divinyl ether, an alkoxy polyalkylene glycol vinyl ether or the like.

Further, as another component, a copolymerizable (meth)acrylic monomer, a (meth)acrylamide monomer, a dialkyl-substituted acrylamide monomer, which contains an alkylene oxide, may be appropriately blended. A known additive such as a surfactant, a curing accelerator, a plasticizer, a filler, a curing inhibitor, a processing aid, an anti-aging agent, and an antioxidant. These may be used alone or in combination of two or more.

By copolymerizing a (meth)acrylic acid alkyl ester having an alkyl group having 4 to 10 carbon atoms and a hydroxyl group-containing copolymerizable monomer and a carboxyl group-containing copolymerizable monomer, it can be synthesized and used as the present invention. A (meth)acrylic polymer of a main component of the adhesive composition. The polymerization method of the (meth)acrylic polymer is not particularly limited, and an appropriate polymerization method such as solution polymerization or emulsion polymerization can be used. In the (meth)acrylic polymer, a polyalkylene glycol mono(meth)acrylate monomer, a hydroxyl group-free nitrogen-containing vinyl monomer, or an alkoxy group-containing (methyl group) may be used. Other monomers such as an alkyl acrylate monomer and a quaternary ammonium salt type ionic compound containing an acrylonitrile group are copolymerized. The adhesive composition of the present invention can be prepared by blending a crosslinking agent, an antistatic agent, and any appropriate additives in the above (meth)acrylic polymer.

Further, the acid value of the (meth)acrylic polymer is preferably 0.01 to 8.0. Thereby, it is possible to improve the staining property and improve the performance of preventing the occurrence of the adhesive residue. Here, the "acid value" is one of the indexes indicating the acid content, and is expressed by the number of mg of potassium hydroxide required to neutralize 1 g of the carboxyl group-containing polymer.

It is preferable that the adhesive layer obtained by crosslinking the above-mentioned adhesive composition has a bonding force of 0.3 to 0.1 N/25 mm at a peeling speed of 0.3 m/min in a low speed region, and a peeling speed of 30 m/min at a high speed region. The bonding force is 1.0N/25mm or less. Thereby, it is possible to obtain a performance in which the change in the adhesive force with the peeling speed is small, and it is possible to quickly peel off even in the case of high-speed peeling. Further, even if the surface protective film is temporarily peeled off for re-adhesion, it does not require excessive force and is easily peeled off from the adherend.

The adhesive layer which is preferably obtained by crosslinking the above-mentioned adhesive composition has a surface resistivity of 5.0 × 10 ^{+ 11} Ω / □ or less, and a peeling static voltage of ± 0 to 0.5 kV. Further, in the present invention, the term "±0 to 0.5 kV" means "0 to -0.5 kV" and "0 to +0.5 kV", that is, "-0.5 to +0.5 kV". When the surface resistivity is large, the performance of releasing static electricity due to charging at the time of peeling is inferior. Therefore, by making the surface resistivity sufficiently small, it is possible to reduce the static electricity generated when the adhesive layer is peeled off from the adherend. The generated peeling static voltage can suppress the influence on the electric control circuit or the like of the adherend.

It is preferable that the adhesive layer (crosslinked adhesive) obtained by crosslinking the adhesive composition of the present invention has a gel fraction of 95 to 100%. Since the gel fraction is so high, the adhesive force does not become excessive at the peeling speed in the low-speed region, and the phenomenon of eluting the unpolymerized monomer or oligomer from the (meth)acrylic polymer is lowered, so that the improvement can be improved. Durability under processability, high temperature/high humidity, and suppression of contamination by adherends.

The adhesive film of the present invention is formed by forming an adhesive layer on one or both sides of a resin film, and the adhesive layer is formed by crosslinking the adhesive composition of the present invention. Further, the surface protective film of the present invention is formed by forming an adhesive layer on one side of a resin film, and the adhesive layer is formed by crosslinking the adhesive composition of the present invention. In the adhesive composition of the present invention, since the components are blended with good balance, the antistatic property is excellent, the balance of the adhesive force at the peeling speed in the low speed region and the high speed region is excellent, and durability is obtained. It is also excellent in performance and reworkability (after being drawn on the surface protective film with the pen holder through the adhesive layer, no contamination is transferred to the adherend). Therefore, it can be suitably used as a surface protective film of a polarizing plate, a phase difference plate, and an anti-reflection film.

As the base film of the adhesive layer and the release film (separator) which protects the adhesive surface, a resin film such as a polyester film or the like can be used. The base film can be formed on the surface of the resin film opposite to the side on which the adhesive layer is formed by using an anthrone or a fluorine-based release agent, a coating agent, cerium oxide particles or the like. The antifouling treatment can be carried out by an antistatic treatment by coating or mixing of an antistatic agent. In the release film, a release treatment by an anthrone or a fluorine release agent is performed on the surface on the side where the adhesive surface of the adhesive layer is bonded. The adhesive layer for bonding an optical film such as a polarizing plate or a retardation film to an optical member such as a liquid crystal cell or another optical film preferably has sufficient transparency. In addition, in the case of an optical surface protection film such as a surface protective film for a polarizing plate, the base film and the adhesive layer are preferably sufficiently transparent.

When the adhesive film has a substrate film, the adhesive film of the present invention can be suitably used for, for example, a surface protective film, a surface protective film for a polarizing plate, an optical surface protective film, an optical film with an adhesive, and A polarizer or the like of an adhesive.

When the adhesive film does not have a base film, the release film can be formed by laminating the release film on the both sides of one adhesive layer. The composition of the "film". Further, a structure in which an adhesive layer is formed on one surface of the release film to form a "release film/adhesive layer" may be employed. In this case, the release film on both sides can be peeled off sequentially or simultaneously to expose the adhesive surface, and can be bonded to an optical member such as an optical film. Examples of the optical film include a polarizing film, a retardation film, an antireflection film, an anti-glare film, an ultraviolet absorbing film, an infrared absorbing film, an optical compensation film, and a brightness enhancement film. At this time, the adhesive film of the present invention can be used for bonding of a polarizing plate and a display panel. Examples of the display panel include a liquid crystal display device and an organic EL (Organic Electro-Luminescence: OEL), but are not limited thereto. In addition, the adhesive film of the present invention can be used for a material bonding adhesive film constituting a polarizing plate, a peripheral film for a liquid crystal display mainly using a polarizing plate, a film for a touch panel, a film for electronic paper, and an organic film. A film for EL or the like.

Further, an optical film having an adhesive layer may be prepared by laminating the above-mentioned adhesive layer on at least one surface of these optical films. Specifically, “optical film/adhesive layer/optical film”, “optical film/adhesive layer/release film”, “optical film/adhesive layer”, “optical film/adhesive agent” may be mentioned. Layer / optical film / adhesive layer / optical film", "optical film / adhesive layer / optical film / adhesive layer / release film", "release film / adhesive layer / optical film / adhesive The composition of the adhesive layer/release film". For example, in the case of an adhesive layer protected by a release film like "optical film/adhesive layer/release film", the release film is peeled off to expose an image like "optical film/adhesive layer" Such an adhesive layer is bonded to another optical film, whereby a structure in which an adhesive layer is used for interlayer bonding such as "optical film/adhesive layer/optical film" can be obtained. [Examples]

Hereinafter, the present invention will be specifically described based on examples.

<Production of (Meth)Acrylic Polymer> [Example 1] Nitrogen gas was introduced into a reaction apparatus equipped with a stirrer, a thermometer, a reflux condenser, and a nitrogen introduction tube, thereby replacing the air in the reaction apparatus with nitrogen. Then, 80 parts by weight of 2-ethylhexyl acrylate, 10 parts by weight of isodecyl acrylate, 8.5 parts by weight of 8-hydroxyoctyl acrylate, and 1.5 parts by weight of acrylic acid were added to the reaction apparatus, and At the same time, 60 parts by weight of a solvent (ethyl acetate) was added. Then, 0.1 part by weight of azobisisobutyronitrile as a polymerization initiator was added dropwise thereto over 2 hours, and the mixture was reacted at 65 ° C for 6 hours to obtain a weight average molecular weight of 500,000 for use in Example 1 ( Methyl) acrylic polymer solution 1. A part of the (meth)acrylic polymer was used as a sample for measuring an acid value to be described later. [Examples 2 to 6 and Comparative Examples 1 to 3] In addition to the compositions of the respective monomers as described in (A) to (D) in Tables 1 and 2, the above-described Example 1 was used. The (meth)acrylic polymer solution 1 was similarly operated, and the (meth)acrylic polymer solutions used in Examples 2 to 6 and Comparative Examples 1 to 3 were obtained. Further, in Tables 1 and 2, (A) is an alkyl (meth)acrylate having an alkyl group having 4 to 10 carbon atoms, and (B) is an alkyl group having 14 to 18 carbon atoms. The (meth)acrylic acid alkyl ester, (C) is a hydroxyl group-containing copolymerizable monomer, and (D) is a carboxyl group-containing copolymerizable monomer.

<Manufacture of adhesive composition and surface protective film> [Example 1] To the (meth)acrylic polymer solution 1 of Example 1 produced as described above, 2.0 parts by weight of 1-octylpyridine was added.鎓 Dodecylbenzenesulfonate, 0.1 parts by weight of a polyether modified siloxane compound having a HLB of 7 (weight average molecular weight Mw of 10,000), and after stirring, 1.0 part by weight of Coronate HX (hexamethylene) was added. The isocyanurate of the bis-isocyanate compound was stirred and mixed to obtain the adhesive composition of Example 1. The adhesive composition was applied onto a release film composed of a polyethylene terephthalate (PET) film coated with an fluorenone resin, and then dried at 90 ° C to remove the solvent to obtain a bond. The adhesive layer has a thickness of 25 μm . Then, a polyethylene terephthalate (PET) film having an antistatic treatment and an antifouling treatment on one surface is prepared, and the adhesive sheet is transferred to the polyethylene terephthalate (PET). On the surface opposite to the surface on which the antistatic treatment and the antifouling treatment were carried out, a PET film/adhesive layer/release film (coated with an anthrone resin) having antistatic treatment and antifouling treatment was obtained. The surface protective film of Example 1 in which the PET film was laminated. [Examples 2 to 6 and Comparative Examples 1 to 3] The same as the surface protective film of Example 1 except that the composition of each additive was adjusted as described in (E) to (G) of Tables 1 and 2, respectively. The surface protective films of Examples 2 to 6 and Comparative Examples 1 to 3 were obtained. Further, in Tables 1 and 2, (E) is a crosslinking agent, (F) is an antistatic agent, and (G) is a polyether modified siloxane compound.

The numerical values in the parentheses in Table 1 indicate the numerical values of the parts by weight obtained by setting the total amount of the total of the groups (A) to (D) to 100 parts by weight. Further, the compound names corresponding to the abbreviations of the respective components used in Table 1 are shown in Table 2. In addition, Coronate (registered trademark) HX, Coronate HL and Coronate L are trade names of Nippon Polyurethane Industry Co., Ltd., Takenate (registered trademark) D-140N, D-127N, D -110N is the trade name of Mitsui Chemicals Co., Ltd.

<Test method and evaluation> After the surface protective films of Examples 1 to 6 and Comparative Examples 1 to 3 were aged for 7 days in an environment of 23 ° C and 50% RH, the release film (PET coated with an anthrone resin) was peeled off. The film) exposes the adhesive layer and serves as a sample for measuring the surface resistivity. Further, the surface protective film exposed to the adhesive layer is bonded to the surface of the polarizing plate adhered to the liquid crystal cell by the adhesive layer, and left for 1 day, and then subjected to autoclave treatment at 50 ° C and 5 atm. After 20 minutes, it was further allowed to stand at room temperature for 12 hours, and was used as a sample for measuring adhesion, peeling static voltage, reworkability, and durability.

<Acid value> Acid value of (meth)acrylic polymer: The sample was dissolved in a solvent (a solvent in which diethyl ether and ethanol were mixed at a volume ratio of 2:1), and an electric potential difference automatic titrator (AT-610) was used. , manufactured by Kyoto Electronics Industry Co., Ltd.), potentiometric titration was carried out with a potassium hydroxide ethanol solution having a concentration of about 0.1 mol/L, and the amount of the potassium hydroxide ethanol solution required for neutralizing the sample was measured. Then, the acid value was determined according to the following formula. Acid value = (B × f × 5.611) / SB = amount of 0.1 mol / L potassium hydroxide ethanol solution used in the titration (mL) f = 0.1 mol / L potassium hydroxide ethanol solution coefficient (factor) S = test Quality of solid components (g)

<Adhesive strength> The tensile tester was used to peel the above-mentioned measurement sample in a 180° direction at a peeling speed (0.3 m/min) in a low speed region and a peeling speed in a high speed region (30 m/min) (25 mm wide) The surface protective film was bonded to the surface of the polarizing plate, and the peeling strength was measured, and the peeling strength was used as the adhesive force.

<Surface resistivity> After aging, before peeling off the polarizing plate, peeling off the peeling film (PET film coated with an oxime resin) to expose the adhesive layer, using a resistivity meter HirestaUP-HT450 (Mitsubishi Chemical Analysis Technology ( The company was manufactured by Mitsubishi Chemical Analytech Co., Ltd., and the surface resistivity of the adhesive layer was measured.

<Peel static voltage> Using a high-precision electrostatic sensor SK-035, SK-200 (manufactured by Keyence Corporation), the measurement sample obtained above was pulled at 30 m/min. When the stretching speed is 180°, the voltage generated by the polarizing plate is charged (static voltage), and the maximum value of the measured value is taken as the peeling static voltage.

<Reworkability> After drawing on the surface protective film of the measurement sample obtained above with a ball pen (loading: 500 g, three times back and forth), the surface protective film was peeled off from the polarizing plate, and the surface of the polarizing plate was observed to confirm whether or not The polarizing plate transferred the contamination. Evaluation target criterion: when the contamination is not transferred to the polarizing plate, it is evaluated as "○"; when it is confirmed that the trajectory drawn along the atomic pen is at least partially transferred to the pollution, it is evaluated as "△"; when it is confirmed that the trajectory drawn along the atomic pen has The contamination was transferred and evaluated as "X" when the adhesion of the adhesive was confirmed from the surface of the adhesive.

<Durability> The measurement sample obtained above was placed in an environment of 60° C. and 90% RH for 250 hours, and then taken out and allowed to stand at room temperature for further 12 hours, and then the adhesion was measured to confirm the initial adhesion. Whether there is a significant increase in comparison. Evaluation target standard: When the adhesion after the test was 1.5 times or less of the initial adhesion, it was evaluated as "○", and when it was more than 1.5 times, it was evaluated as "X".

<Wettability> The surface of the polarizing plate to which the anti-glare treatment was applied was applied to only one end of the measurement sample having a length of 2.5 cm width × 5 cm, and the measurement sample was uniformly wetted and bonded as a whole. The time required for the surface of the polarizing plate. Evaluation target datum: When the time required for uniform wetting on the whole was less than 15 seconds, it was evaluated as "○"; when the time required for uniform wetting on the whole was 15 seconds or more and less than 30 seconds, it was evaluated as " △"; when the time required for uniform wetting on the whole was 30 seconds or more, it was evaluated as "x".

<dent test> On the surface of the measurement sample, a dip test jig (jig) having 100 protrusions in 5 cm × 5 cm was placed, and a load of 1 kg was applied for 1 day, and 5 cm × 5 cm was placed. The measurement sample was bonded to a polarizing plate, and the number of defects (bubbles) due to poor adhesion due to the measurement of the dent on the surface of the sample after the bonding was measured. Evaluation target criterion: When the number of defects is 0 to 5, the evaluation is "○"; when the number of defects is 6 to 10, the evaluation is "△"; when the number of defects is 11 or more , the evaluation is "X".

The evaluation results are shown in Table 3. Further, in the surface resistivity, by "mE + n" to represent "m × 10 ^{+ n"} (where, m is an arbitrary real numbers, n-is a positive integer).

In the surface protective films of Examples 1 to 6, the adhesive strength at a peeling speed of 0.3 m/min in a low speed region was 0.05 to 0.1 N/25 mm, and the peeling force at a peeling speed of 30 m/min in a high speed region was 1.0. Below N/25 mm, the surface resistivity is 5.0 × 10 ⁺¹¹ Ω/□ or less, and the peeling static voltage is ±0 to 0.5 kV. In addition, after the surface protective film was drawn through the adhesive layer via the pen holder, the adhesion to the adherend was not transferred, and the durability after leaving it in an environment of 60° C. and 90% RH for 250 hours was also excellent. That is, the surface protective film of the present invention satisfies all the performance requirements for the adhesive layer composed of the following five items: (1) achieving the balance of the adhesive force at the peeling speed of the low speed region and the high speed region; Preventing the occurrence of adhesive residue; (3) having excellent antistatic properties; (4) having reworkability; and (5) preventing defects such as dents caused by external stress.

The surface protective film of Comparative Example 1 may be due to the absence of an alkyl (meth)acrylate having an alkyl group having 14 to 18 carbon atoms, a hydroxyl group-containing copolymerizable monomer, and no In the case of the carboxyl group-containing copolymerizable monomer, the peeling speed in the low-speed region is small at a peeling speed of 0.3 m/min, the surface resistivity and the peeling static voltage are high, and the durability is poor. Moreover, its wettability and dent test were also slightly worse. The surface protective film of Comparative Example 2 had a high surface resistivity and a peeling static voltage because it did not contain an antistatic agent. Further, the alkyl (meth)acrylate having an alkyl group having 14 to 18 carbon atoms is not contained, and the hydroxyl group-containing copolymerizable monomer is too large, and the durability is somewhat inferior. Moreover, the results of the wettability and dent test were poor. The surface protective film of Comparative Example 3 may be composed of an alkyl (meth)acrylate having no alkyl group having 14 to 18 carbon atoms and a copolymerizable monomer having a carboxyl group. The surface resistivity and the peeling static voltage are high, and the reworkability is slightly inferior. In addition, the results of the dent test were poor. As described above, with respect to the surface protective films of Comparative Examples 1 to 3, it was not possible to simultaneously satisfy all the performance requirements for the adhesive layer composed of the following five items: (1) Obtaining the peeling speed of the low speed region and the high speed region Balance of adhesion; (2) prevention of adhesive residue; (3) excellent antistatic properties; (4) reworkability; and (5) prevention of dents due to external stress Disadvantages. (industrial use)

The surface protective film of the present invention has antistatic property, excellent balance of adhesive force at a peeling speed in a low speed region and a high speed region, and durability and reworkability (protection of the surface with a ball pen through an adhesive layer) It is also excellent in that it is not contaminated by the adherend after the film is drawn on the film. Therefore, it can be suitably used as a surface protective film of a polarizing plate, a phase difference plate, and an antireflection film, and it is industrially useful.

no

Claims (15)

An adhesive composition comprising an antistatic agent and a (meth)acrylic polymer, wherein the (meth)acrylic acid is based on 100 parts by weight of the (meth)acrylic polymer. The polymer is 55 to 97.5 parts by weight of an alkyl (meth)acrylate having an alkyl group having 4 to 10 carbon atoms, and 1 to 30 parts by weight of an alkyl group having 14 to 18 carbon atoms. (meth)acrylic acid alkyl ester, 0.1 to 15 parts by weight of a hydroxyl group-containing copolymerizable monomer, and 0.1 to 2 parts by weight of a carboxyl group-containing copolymerizable monomer, which are copolymerized with respect to 100 parts by weight a (meth)acrylic polymer, the binder composition further comprising 0.1 to 5 parts by weight of a crosslinking agent, the (meth)acrylic polymer having an acid value of 0.01 to 8.0, the antistatic agent being a melting point It is an ionic compound of 30 to 50 °C. The adhesive composition of claim 1, wherein the alkyl (meth)acrylate having an alkyl group having 4 to 10 carbon atoms is selected from the group consisting of butyl (meth)acrylate, Isobutyl (meth)acrylate, amyl (meth)acrylate, hexyl (meth)acrylate, heptyl (meth)acrylate, octyl (meth)acrylate, isooctyl (meth)acrylate, Compound group consisting of 2-ethylhexyl (meth)acrylate, decyl (meth)acrylate, isodecyl (meth)acrylate, decyl (meth)acrylate, isodecyl (meth)acrylate One or two or more of the alkyl (meth)acrylates having an alkyl group having 14 to 18 carbon atoms are selected from the group consisting of isotetradecyl (meth)acrylate and (meth) Isohexadecyl acrylate, isostearyl (meth) acrylate, tetradecyl (meth) acrylate, cetyl (meth) acrylate, octadecyl (meth) acrylate One or more of the compound groups consisting of the base esters. The adhesive composition according to claim 1 or 2, further comprising a polyether modified siloxane compound having an HLB of 7 to 15 as an antistatic adjuvant. The adhesive composition according to any one of claims 1 to 3, wherein the hydroxyl group-containing copolymerizable monomer is selected from the group consisting of 8-hydroxyoctyl (meth)acrylate, (methyl) ) 6-hydroxyhexyl acrylate, 4-hydroxybutyl (meth) acrylate, 2-hydroxyethyl (meth) acrylate, N-hydroxy (meth) acrylamide, N-methylol (methyl) At least one or more of the compound groups consisting of acrylamide and N-hydroxyethyl (meth) acrylamide. The adhesive composition according to any one of claims 1 to 4, wherein the carboxyl group-containing copolymerizable monomer is selected from (meth)acrylic acid, carboxyethyl (meth)acrylate , (meth)acrylic acid carboxypentyl ester, 2-(meth)acryloxyethyl hexahydrophthalic acid, 2-(methyl)acryloxypropyl hexahydrophthalic acid, 2- (Meth) propylene oxiranyl ethyl phthalate, 2-(methyl) propylene methoxyethyl succinic acid, 2-(methyl) propylene methoxyethyl maleic acid, carboxy polyene At least one or more of the compound group consisting of ester mono(meth)acrylate and 2-(meth)acryloxyethyltetrahydrophthalic acid. The adhesive composition according to any one of claims 1 to 5, further comprising a polyether modified siloxane compound having an HLB value of 7 to 15 and a molecular weight of 10,000 or less as an antistatic adjuvant. . The adhesive composition according to any one of claims 1 to 6, wherein the crosslinking agent is a trifunctional or higher isocyanate compound. An adhesive film formed by forming an adhesive layer on one side of a resin film, the adhesive layer being crosslinked by the adhesive composition according to any one of claims 1 to 7. Made. A surface protective film using the adhesive film of item 8 of the patent application. A surface protective film for a polarizing plate which uses an adhesive film as in the eighth aspect of the patent application. An optical surface protective film using the adhesive film of claim 8 of the patent application. An adhesive film for bonding a polarizing plate and a display panel, which uses an adhesive film as in the eighth aspect of the patent application. An adhesive film for bonding an optical film material constituting a polarizing plate, which uses an adhesive film as in the eighth aspect of the patent application. An optical film for a touch panel using an adhesive film as in the eighth aspect of the patent application. An optical film for electronic paper using the adhesive film of item 8 of the patent application.